In a previous study the A. nidulans polarity mutant swoF1 was found to be mutated in a gene encoded a protein N-myristoyl transferase (NMT). NMTs transfer the 14 carbon fatty acid myristate to the N-terminus of a small group of proteins. This modification allows otherwise cytoplasmic proteins to associate with membranes. We hypothesize that a myrisotylated protein downstream of SwoF plays an important role in growth polarity. Six suppressor of swoF1 (ssf) mutants have been identified. Genetic analysis has shown that all six mutations are extragenic to swoF. At least two distinct, reduced growth phenotypes are observed when each ssf mutant is released from the swoF background. Interestingly, ssfA, ssfC and ssfD secrete a red pigment into the medium similar in color to ascoquinone, as made during ascosporogenesis. This is of particular note, since the G alpha proteins GanA, GanB, and FadA are likely targets for myristoylation. The distinct reduced growth phenotype of each mutant allows for cloning by complementation. To date ssfD has been complemented using a plasmid based genomic library, but the complementing clone has not been analyzed. Continued analysis of these mutants will be discussed. Progress using an in vivo labeling approach to ascertain myrisotylated targets of SwoF will be discussed.
Full conference title:
23rd Fungal Genetics Conference
- Fungal Genetics Conference 23rd (2002)